Fig. 1.
Deuterostome ASICs identified through phylogenetic and functional analyses. (A) Maximum-likelihood tree inferred from alignment of 17 ASIC-like subunits from one vertebrate, one tunicate, two cephalochordates, one hemichordate, and two echinoderms, rooted to mouse BASIC. (B and C) pH-gated currents in oocytes expressing indicated cRNAs. Resting pH 7.5 (B) or 9.0 (C). [Scale bars: x 20 s; y 0.1 μA (B. belcheri A and P. flava B) or 3 μA (all others).] B. belcheri BChi is a chimera (SI Appendix, Supplementary Text). (D) In situ hybridization targeting O. dioica group A ASIC (black arrows). Illustrated CNS landmarks: CaG, caudal ganglion; ccn, cerebrocaudal nerve; CeG, cerebral ganglion; fbn, first brain nerve. (Inset) Control experiment using complementary sense probe showing nonspecific staining in the pharynx (yellow arrows in both sense and antisense experiments).